Implement the NeoDisplay render() method

The render() method needs to return a big string that represents what should be printed to the screen. It will have do rearrange the array of '*' (on), and ' ' (off) values so that the serpentine ordering is respected. For the first version, you can assume that we have a single 8x32 sheet. Probably want so leave horizontal spaces between the pixels, since display characters tall and narrow. Experiment to see if you need a vertical space or not.

Start at the NeoDisplay.render() entry point and inspect how the array of '*' and ' ' values is stored. Implement output for a single 8x32 sheet using serpentine ordering, then verify that the returned string has readable horizontal spacing between display characters.

Written by the indexing model from the issue text.